my 2 cents...

1. get a feel for the table / players (is it tight, loose etc) this is the key to knowing what you can / can't get away with.

2. decide how you want to play it - if you raise then how much? (table knowledge also important here) can you slow play it or use it to reraise the maniac sitting beside you who will raise with anything if no-one else has raised...

3. you raise and miss the flop but it's raggy and rainbow - throw out a bet (two thirds / full pot - your call) and again, depending on the table you may well take it down there - people don't know if you have overcards or overpair remember. (i've taken to raising a set amount regardless of cards to this very end - AJ gets the same raise as AA) if you get called and don't improve on the turn then check / fold unless you have a read on the caller and figure he has overcards too and not as good as yours...

3a. you raise and miss the flop but it's a connected (flush or straight) board - probably same as above to be honest. you have the lead in the hand because you raised it pf - if you check then you give that up - unless of course you hit a monster at which point it's a whole different story

3b. you raise and miss the flop but there are high cards present - as above again - to be honest, i've found you are more likely to take it down if there are high cards present - people more likely to believe the bet.

you have to know the table though - that's most of the battle. as with most things in this game - there are no hard and fast rules. should you raise, should you bet, should you fold? well, you see it depends...

hope that's halfway useful.